I am 39, American, white and I am taking a math class at my local college. I am the oldest person in the class by far. I get A's, so do a few others. Most get C

I am 39, American, white and I am taking a math class at my local college. I am the oldest person in the class by far. I get A's, so do a few others. Most get C's. I do every homework problem. I do variations of the homework problems. I spend at least 6 hours outside of our class time (3 hours) doing the math. When we have tests the Instructor gives us problems that are not like the homework where she can see if we can evaluate and apply the concepts to things we haven't yet seen.